A01_PWS_Attachment_1.pdf

Attachment 1

Variable Frequency Drive Essential Salient Features:

General Requirements:

1. Provide complete variable speed drive(s) as specified herein. All standard and optional features requested shall be included within the VFD enclosure unless otherwise specified. Drive shall be for variable torque load, unless otherwise noted.

2. The variable speed drive shall convert three-phase, 60 HZ utility power to adjustable voltage and frequency, three-phase, AC power for step- less motor speed control from 10% to 100% of the motor's 60 Hz speed. Input voltage shall be 480 VAC, three phase.

3. The VFD power input stage shall convert three-phase AC line power to a fixed DC bus voltage.

This will be accomplished with a six-pulse input design, and the input voltage rectifier shall employ a three phase full-wave diode bridge with metal oxide varistor (MOV) three phase protection; VFD’s utilizing controlled SCR rectifiers shall not be acceptable.

4. Displacement power factor shall not be less than 0.95 throughout the speed range.

5. The VFD output power shall vary frequency to the motor from 6 to 60 Hz with resultant motor speed varying at the motor nameplate rated speed, with output voltage variation from zero to motor rated voltage for optimum volts per hertz (V/Hz) ratio for pump loads.

6. Output current shall be rated intermittently at 105% of motor full load amps (FLA) for 1 minute based upon VFD's variable torque FLA rating. The output must be a voltage source type generating a sine coded PWM waveform utilizing an asynchronous carrier frequency (output transistor switching frequency is to be independent of drive output frequency). This carrier frequency shall be adjustable to minimize harmonically induced noise or vibration.

7. The VFD selected must be able to source 90% of the motor’s full load nameplate amperage (fundamental RMS) on a continuous basis, and capable of running the motor at its nameplate RPM, voltage, current, and slip without having to utilize the service factor of the motor.

8. The VFD shall produce an output waveform capable of handling maximum motor cable distances of up to 500 ft. (unshielded) without tripping or derating.

9. VFD shall automatically boost power factor at lower speeds.

10. The VFD shall be capable of running variable torque loads. In variable torque applications, the

VFD shall provide a CT-start feature and be able to provide full torque at any speed up to the base speed of the motor. In either CT or VT mode, the VFD shall be able to provide its full rated output current continuously and 105% of rated current for 60 seconds.

11. An initial ramp function shall be available to provide a user selectable ramp, up to 60 seconds, for applications requiring a faster or slower ramp than the normal ramp.

12. Switching of the input power to the VFD shall be possible without interlocks or damage to the VFD at a minimum interval of 2 minutes.

13. Switching of power on the output side between the VFD and the motor shall be possible with no limitation or damage to the VFD and shall require no additional interlocks.

14. The VFD shall have temperature controlled cooling fans for quiet operation, minimized internal losses, and greatly increased fan life.

15. VFD shall provide full torque to the motor, given input voltage fluctuations of up to +10% to –

10% of the rated input voltage. Line frequency variation of ± 2% shall be acceptable.

16. The VFD shall provide internal DC link reactors to minimize power line harmonics and to provide near unity power factor. DC Link reactor shall be installed so that power fluctuations to the DC Capacitors shall be reduced to increase Capacitor life.

17. VFD’s shall be capable of operation from an emergency generator without concern. The VFD shall provide a 3% impedance line side reactor.

Features:

1. The VFD’s shall be housed in a NEMA 4X enclosure.

2. The following display/control parameters shall be located on the front of the enclosure:

a. Hand/Off/Auto selector to start and stop the motor. In the auto position, the drive shall start/stop from a remote contact closure. In the auto position, motor speed shall be determined by the follower signal. In the manual position, motor speed shall be determined by manual adjustment.

b. Power on indication that the VFD is being supplied by the power line.

c. Fault indication that the VFD has tripped on a fault condition.

d. Display shall indicate load parameters such as load percent, frequency or running load amps.

3. A set of form C, dry contacts to indicate when the VFD is in the run mode.

4. A set of form C, dry contacts to indicate when the VFD is in the fault mode.

5. Input terminations for safety interlocks such as low wet well and high wet well level.

6. For a fault condition other than a ground fault, short circuit or internal fault, an auto restart function shall provide up to 6 programmable restart attempts. The time delay before restart attempts shall be a minimum of 30 seconds. This function permits automatic restarting after the drive controller detects a fault, provided that the other operating functions are correct, a run command is present, and the fault has disappeared. This shall be a function that is field selectable.

7. Speed Reference Input: Shall accept both a manual speed signal and a 4-20 mA speed reference analog input signal.

8. Feedback Signal: Provide 4-20 mA analog output signal to indicate actual operating speed of

VFD.

9. The VFD shall have the ability to ride through a power loss of 5 cycles or less.

10. The VFD shall have the ability to automatically restart on loss of power.

11. The VFD shall have the ability to safely detect and react to a ground fault. There shall be no risk of fire or electric shock as a result of the ground fault.

Protective Features:

1. VFD shall have input surge protection utilizing MOV’s, spark gaps, and Zener diodes to withstand surges of 2.3 times line voltage for 1.3 msec.

2. VFD shall include circuitry to detect phase imbalance and phase loss on the input side of the

VFD.

3. VFD shall auto-derate the output voltage and frequency to the motor if an input phase is lost.

This result will maintain operation without decreasing the life expectancy of the VFD. The use of this feature shall be user selectable and export a warning during the event.

4. Dry-pump detection shall be available to detect if the pump has run dry. If this condition occurs, the drive will be safely stopped. A timer shall be included to prevent nuisance tripping.

5. VFD shall include current sensors on all three-output phases to detect and report phase loss to the motor. The VFD will identify which of the output phases is low or lost.

6. VFD shall auto-derate the output voltage and frequency to the motor in the presence of sustained ambient temperatures higher than the normal operating range, so as not to trip on an inverter temperature fault. The use of this feature shall be user- selectable and a warning will be exported during the event. Function shall reduce switching frequency before reducing motor speed.

7. VFD shall auto-derate the output frequency by limiting the output current before allowing the VFD to trip on overload. The speed of the load can be reduced, but not stopped.

8. VFD shall provide UL Listed Class 10 separate overload protection for each motor controlled to comply with NEC Article 430.

9. Protection against output current overload and over current.

10. Protection against over temperature within the VFD enclosure.

11. Protection against over voltage on the DC bus.

12. DC bus discharge circuit for protection of service personnel.

13. Insensitive to incoming power phase sequence.

14. VFD shall minimize motor bearing and insulation damage by minimizing dV/dt spikes to < 1600 volts/microsecond.

15. VFD shall inherently protect motor from high voltage dV/dt stress, independent of cable length to motor. VFD shall be designed to produce no standing waves or over-voltage conditions based on a cable length of at least 500 feet. The VFD shall include an output filter to meet this requirement, it shall be an integral part of the VFD system and included within the VFD’s enclosure.

16. Motor life expectancy should not be compromised in any way by operation with the VFD.

17. The VFD shall be able to withstand the following fault conditions without damage to the power circuit components:

a. Failure to connect a motor to the VFD output.

b. VFD output open circuit that may occur during operation.

18. The VFD shall be protected from damage due to the following:

a Single phase fault or three phase short circuit on VFD system output terminals.

b Loss of input power due to opening of input disconnect device or utility power failure during operation.

c Loss of one phase of utility power d Motor regeneration due to backspin or loss of VFD input power.

Adjustment:

1. Maximum speed, adjustable 50-100% base speed.

2. Minimum speed, adjustable 0-50% base speed.

3. Acceleration time, adjustable 3 to 1800 seconds.

4. Deceleration time, adjustable 3 to 1800 seconds with override circuit to prevent nuisance trips if decel time is set too short.

5. Current limit, adjustable 0-100%.

6. VFD shall provide an alphanumeric backlit display keypad which may be remotely mounted using a standard 9-pin cable. VFD may be operated with keypad disconnected or removed entirely. Keypad may be disconnected during normal operation without the need to stop the motor or disconnect power to the VFD.

7. VFD Keypad shall feature an INFO key that, when pressed, shall display the contents of the programming manual for the parameter that is currently viewed on the display. The description shall explain the feature and how the settings can be made by the operator.

8. VFD shall display all faults in plain text; VFD’s which can display only fault codes are not acceptable.

9. The keypad shall feature a multi-line graphical display and be capable of digitally displaying up to five separate operational parameters or status values simultaneously (including process values with the appropriate engineering unit) in addition to Hand/Off/Auto, Local/Remote, and operating status.

10. Keypad shall provide an integral H-O-A (Hand-Off-Auto) and Local Remote selection capability, and manual control of speed locally without the need for adding selector switches, potentiometers, or other devices.

11. VFD keypad shall be capable of storing drive parameter values in non-volatile RAM uploaded to it from the VFD, and shall be capable of downloading stored values to the VFD to facilitate programming of multiple drives in similar applications, or as a means of backing up the programmed parameters.

12. VFD Display shall have the ability to display 5 different parameters pertaining to the VFD or the load including: current, speed, DC bus voltage, output voltage, input signal in mA, or other values from a list of different user-selectable parameters.

13. VFD display shall indicate which digital inputs are active and the status of each relay.

14. VFD display shall indicate the value of any voltage or current signal, including the engineering units of measurement, connected to the analog input terminals.

15. VFD display shall indicate the value of the current at the analog output terminals, including the engineering units of measurement.

16. A red FAULT light, a yellow WARNING light and a green POWER-ON light shall be provided.

These indications shall be visible both on the keypad and on the VFD when the keypad is removed.

17. Two-level password protection shall be provided to prevent unauthorized changes to the programming of the VFD. The parameters can be locked via a digital input and/or the unit can be programmed not to allow an unauthorized user to change the parameter settings.

18. A quick setup menu with factory preset typical parameters shall be provided on the VFD to facilitate commissioning. Use of macros shall not be required.

19. A digital elapsed time meter and kilowatt hour meter shall be provided in the display.

20. VFD shall offer as standard an internal clock. The internal clock can be used for: Timed

Actions, Energy Meter, Trend Analysis, date/time stamps on alarms, Logged data, Preventive maintenance, or other uses. It shall be possible to program the clock for Daylight Saving Time / summertime, weekly working days or non-working days including 20 exceptions (holidays, etc.). It shall be possible to program a Warning in case the clock has not been reset after a power loss.

21. A battery back-up option shall be provided to maintain internal clock operation during power interruptions. Battery life shall be no less than 10 years of normal operation.

22. VFD shall provide full galvanic isolation with suitable potential separation from the power sources (control, signal, and power circuitry within the drive) to ensure compliance with PELV requirements and to protect PLC’s and other connected equipment from power surges and spikes.

23. All inputs and outputs shall be optically isolated. Isolation boards between the VFD and external control devices shall not be required.

24. There shall be six fully programmable digital inputs for interfacing with the systems external control and safety interlock circuitry. Two of these inputs shall be programmable as inputs or outputs.

25. The VFD shall have two analog signal inputs. Inputs shall be programmable for either 0- 10V or 0/4-20 mA.

26. One programmable analog output shall be provided for indication of the drive status. This output shall be programmable for output speed, voltage, frequency, motor current and output power. The analog output signal shall be 0/4-20 mA.

27. The VFD shall provide two user programmable relays with 75 selectable functions. Two form ‘C’ dry contact relay outputs shall be provided.

28. Floating point control interface shall be provided to increase/decrease frequency in response to external switch closures.

29. The VFD shall accept a N.C. motor temperature over-temperature switch input, as well as possess the capability to accept a motor thermistor input.

30. The VFD shall store in memory the last 10 faults with time stamp and recorded data.

31. VFDs shall be adjusted to keep startup current to less than 1.5x Full Load Current.

Service Conditions:

1. Operate 75 HP centrifugal pump motor.

2. Ambient temperature, -10 to +40oC (14 to 104oF) within an existing pump station with limited ventilation.

3. 0 to 95% relative humidity, non-condensing.

4. Elevation to 500feet without derating.

5. AC line voltage variation, -10% to +10% of nominal.

6. The unit shall be wall-mounted or securely mounted to unistrut components that will allow easy access of positioning gantry device for motor/pump removal from concrete base. Actual positioning of VFD’s shall be approved by the Technical Representative.

END OF ATTACHMENT 1